Fig. 1.

Preferential expression of NKG2D on the CD4⁺CD28^– T cell subset in RA patients. (A and B) Three-color flow cytometry shows that CD4⁺ T cells among normal PBL are negative for NKG2D, whereas significant proportions (25% in this representative sample) from RA patients are positive. (C and D) Among gated CD4⁺ T cells from RA PBL, NKG2D expression is preferentially associated with the CD28^– subset. The sample numbers tested are indicated in the text. (E and F) This association is confirmed with freshly isolated CD4⁺CD28^– synovial T lymphocytes (STL). The results shown are representative of five samples. Numbers in dot plots indicate percentages of cells in quadrants.